As explained in 1407814240-4275-1-git-send-email-decui@xxxxxxxxxxxxx: > hyperv_keyboard invokes serio_interrupt(), which needs a valid serio > driver like atkbd.c. atkbd.c depends on libps2.c because it invokes > ps2_command(). libps2.c depends on i8042.c because it invokes > i8042_check_port_owner(). As a result, hyperv_keyboard actually > depends on i8042.c. > > For a Generation 2 Hyper-V VM (meaning no i8042 device emulated), if a > Linux VM (like Arch Linux) happens to configure CONFIG_SERIO_I8042=m > rather than =y, atkbd.ko can't load because i8042.ko can't load(due to > no i8042 device emulated) and finally hyperv_keyboard can't work and > the user can't input: https://bugs.archlinux.org/task/39820 > (Ubuntu/RHEL/SUSE aren't affected since they use CONFIG_SERIO_I8042=y) The transitive dependency on i8042.c is non-trivial--there appears to be no obvious way to untangle it other than by duplicating much of atkbd.c within hyperv-keyboard--so we employ a simple workaround: keep i8042.ko loaded even if no i8042 device is detected, but set a flag so that any calls into the module simply return (since we don't want to try to interact with the non-existent i8042). This allows atkbd.c and libps2.c to load, solving the problem. Signed-off-by: Mark Laws <mdl@xxxxxxxx> --- drivers/input/serio/i8042.c | 41 ++++++++++++++++++++++++++++++++++------- 1 file changed, 34 insertions(+), 7 deletions(-) diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c index 4541957..4d49496 100644 --- a/drivers/input/serio/i8042.c +++ b/drivers/input/serio/i8042.c @@ -132,6 +132,7 @@ struct i8042_port { static struct i8042_port i8042_ports[I8042_NUM_PORTS]; +static bool i8042_present; static unsigned char i8042_initial_ctr; static unsigned char i8042_ctr; static bool i8042_mux_present; @@ -163,6 +164,9 @@ int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str, unsigned long flags; int ret = 0; + if (!i8042_present) + return ret; + spin_lock_irqsave(&i8042_lock, flags); if (i8042_platform_filter) { @@ -184,6 +188,9 @@ int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str, unsigned long flags; int ret = 0; + if (!i8042_present) + return ret; + spin_lock_irqsave(&i8042_lock, flags); if (i8042_platform_filter != filter) { @@ -311,7 +318,10 @@ static int __i8042_command(unsigned char *param, int command) int i8042_command(unsigned char *param, int command) { unsigned long flags; - int retval; + int retval = 0; + + if (!i8042_present) + return retval; spin_lock_irqsave(&i8042_lock, flags); retval = __i8042_command(param, command); @@ -1380,6 +1390,9 @@ bool i8042_check_port_owner(const struct serio *port) { int i; + if (!i8042_present) + return false; + for (i = 0; i < I8042_NUM_PORTS; i++) if (i8042_ports[i].serio == port) return true; @@ -1569,13 +1582,17 @@ static int __init i8042_init(void) dbg_init(); + i8042_present = false; + err = i8042_platform_init(); if (err) return err; err = i8042_controller_check(); - if (err) - goto err_platform_exit; + if (err) { + pr_info("Staying resident in case of module dependencies\n"); + goto out; + } pdev = platform_create_bundle(&i8042_driver, i8042_probe, NULL, 0, NULL, 0); if (IS_ERR(pdev)) { @@ -1585,7 +1602,9 @@ static int __init i8042_init(void) bus_register_notifier(&serio_bus, &i8042_kbd_bind_notifier_block); panic_blink = i8042_panic_blink; + i8042_present = true; +out: return 0; err_platform_exit: @@ -1595,12 +1614,20 @@ static int __init i8042_init(void) static void __exit i8042_exit(void) { - platform_device_unregister(i8042_platform_device); - platform_driver_unregister(&i8042_driver); + if (i8042_present) { + platform_device_unregister(i8042_platform_device); + platform_driver_unregister(&i8042_driver); + } + i8042_platform_exit(); - bus_unregister_notifier(&serio_bus, &i8042_kbd_bind_notifier_block); - panic_blink = NULL; + if (i8042_present) { + bus_unregister_notifier(&serio_bus, + &i8042_kbd_bind_notifier_block); + panic_blink = NULL; + } + + i8042_present = false; } module_init(i8042_init); -- 2.8.0 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
